Virus Watch: Counting Viruses

In this episode of Virus Watch, I show how to do my favorite assay in all of virology - the plaque assay.

[@mine1731]

Your passion is contagious. Keep up the good work!

[@kiankelly6442]

You should have said infectious

[@zuhairreza]

@@kiankelly6442 Right!

[@richcondit3829]

This brings tears to my eyes. So beautiful.

[@adrianwoodlock8433]

Are controls done with this?

[@sawairagul251]

😂🤣

[@tarahaddad6776]

This was the best, most comprehensive explanation I could find of plaque assays, thank you so much!!

[@anonimous__user]

You are the coolest virology professor I've ever seen! Keep up with the great work and thank you!

[@SvenEnterlein]

When we run neutralization studies at our company I have learned to prefer plaque and immunoplaque assays over any other simply because I have more confidence in them. It is so nice to actually see the reduction in number of plaques as compared to any kind of optical density reading. We use 96-well plates and multichannel pipettors for dilutions (note: we change tips between each dilution) and 24-well plates for the titration. Have you ever used microcellulose instead of agarose? We've seen much better results for most viruses!

[@yatrix3057]

I love your teaching methods. Thank you so much for sharing your experience and knowledge.You make virology easy.

[@jballenger9240]

Great lesson, clearly presented! Memory lane for me (but no tears, Rich). I worked as a most jr. research assistance in Seymour Lederberg's lab at Brown counting placques in early-mid '70s; an incredible experience. As always, thank you. Johnye

[@______6879]

Thank you so much. I will definitely be watching your channel from now on

[@eveeart7421]

Extremely well paced and presented. Thank you so much!

[@huthaifajasem6555]

Thank you so much for sharing your experience with us.

[@quinncochran2551]

This was EXTREMELY helpful! Thank you for your help!

[@TheGJOSHI]

We performed a slightly different procedure. It's great that technology enables us to learn from the best people in this field. Very informative! Thank You so much!

[@rajarangpuri6243]

Excellent presentation, Professor!

[@josetorres3514]

Thank you very much Dr. Racaniello, this was very helpful.

[@marvelgaming4666]

i haven't heard anybody said so well about a tedious process. Great Sir

[@PollyNature98]

splendid and so proud of your hard work.

[@odracirman12]

Thanks I had been trying to understand how it worked and now it's finally clear

[@worldwideweblearning]

Your explanations and tutorials worth more than a $4000 course I have done locally before knowing your channel and subscribed :-). Great thanks Vincent

[@the-random-earthcollection9263]

Great Work Prof. Racaniello.. thank you for teaching us

[@MarioDallaRiva]

Bravo, Dott. Racaniello!! 👏🏻👏🏻 and of course, Dr. Amy too!

[@TheUmaryousaf]

excellent sir, so clear and understandable for layman as well, informative and to the point, thank you.

[@ceel5869]

thank you for this.. you explain well and you are calm. This will surely help me in my experiment next week.

[@Courtny-cq4pl]

Your plate background made my day!

[@kiavashkiaee5565]

Fantastic explanation! GREAT JOB!

[@sheylanabdullah6151]

Thank you so much for sharing your experience

[@theprince2080]

Informative! i wonder if there is a similar technique that we can use to quantify "infectiousness" for other types of microorganisms like bacteria, fungi... etc Thank you!

[@jakiztochlopiec]

Amazing video. very useful. thanks a lot

[@michellemariemartin]

Thank you, sir. This was very helpful.

[@zuhairreza]

I’m studying for my Virology class, and this was helpful. Interested in seeing more science videos from you. Subscribed. : )

[@ignaciobaudino8263]

Thanks for the video! very simple for understanding this method

[@barryvaughan7078]

Ah! Now I understand some of the PCR vs. need-for-plaque-assay discussion re: post-recovery SARS CoVi-2 'virus' or RNA measurements in recent TWiVs! Thanks, Vincent, for the clear explanation.

[@drewetpa]

Yes it's fascinating. The more I learn about testing the more I realise how fallible it is and how preposterous the words of politicians really are. As I understand it with RT-PCR even if the sample is taken competently then sensitivity in UK is somewhere between 60% to 85%. I was asked to do a home test and take my own sample. I believe at drive-in people take their own samples in their vehicles. Good luck trying to take a sample from the back of the throat without touching the teeth, tongue or mouth walls or gagging when the requirement is for 10 seconds on the back of the throat! They only provided one swab. The test arrived 4 days after I reported symptoms and I received the result 8 days after reporting symptoms. As I understand it in mild cases the typical infectious period is around 6 to 8 days starting around 48 hours before symptoms (I know there will be a lot of variation around the median). It's a complete sham and a shambles frankly in the UK. We need a decent spit test at the point of care that takes 15 minutes to get anywhere with routine testing and to make contract tracing even vaguely effective. The LFIA serology tests aren't much better. All they tell you is that you have produced "some" antibodies to "some" antigen in "some" people. (Immunity passports are a ridiculous notion when we don't know what the correlates of protection are). More evidence is mounting of people not seroconverting at detectable or very low levels yet they succesfully clear the virus. IgA? T Cell response? Interferon? I just wash my hands, distance where I can, meditate and watch TWIV and I'm loving my lockdown.

[@entedaralsaadi21]

So beautiful explanation. Many thanks

[@tartanhandbag]

this is awesome. more videos please.

[@rackhi]

This was great!

[@amanitamuscaria5863]

PCR is not meant for virus count. It multiplies exponentially whatever it's set to multiply. We use it for sequencing. That's it's primary purpose. A 96 well assey where 50% are dead is best suited for establishing viral titer.

[@dr.urmibhattacharjee6919]

What an amazing demonstration !! Could you please make a demonstration on quantifying bound-virus on a Staphylococcal cell wall? I am eagerly waiting for your reply.

[@michellezanoni6162]

So informative and pedagogic!!!

[@tumelokgoe6243]

Where can I get this protocol in detail. I love this. What percentage is the agar, what percentage of FBS was used. I need the details of this protocol so that I can use it

[@ThangHuynh10]

Love this video! Make me excited :()

[@ithirstyforknowledge]

Awesome video. Thank you

[@kartoonkiddo9475]

Amazing explanation 👍

[@donaldviszneki8251]

Is determining the infectious:noninfectious ratio used to identify the virus species or just study the properties of a particular strain? If the former, what about flow cytometry?

[@dishaniwickramaarachchi6043]

Excellent presentation🤩🤩

[@Holaquetalcontigo]

Very impressive wall!

[@_anjali_6380]

Very helpful and informative video 👏👏

[@bukolarhoda4863]

So great!!!

[@azulsgilabert9680]

Thanks! Is this method the same for marine bacteriophages?

[@praveenkumartripathi8266]

GREAT TUTORIAL!!!!

[@bardacha100]

You the Best !

[@mrniceguy4277]

What do you think about TCID50?

[@carolinaserranoferrer9435]

Hello!! Mr Vincent I am a student of Colombian Microbiology. This video is so great. Could you tell me what other solution I can use to remove the agar from the plate safely and what is the concentration? I appreciate it a lot. Good vibes.

[@sifirmiaya5841]

great video! easy to understand.

[@ibrahimjouni3458]

amazing!

[@bb-zo8iy]

Since you mentioned polio i would like to know your thoughts on the polio vaccination being contaminated with cv40 or monkey cells?

[@PankajSINGH-gg8tj]

superb sir

[@Igor-vb1hv]

Very interesting!

[@sivasankar372]

Hello Dr Vincent, afte agar overlay, how the cell will survive & get Co2 ?

[@originalsubwayjones]

Excellent vid, Tnx.

[@73Katerchen]

Excellent 👍

[@nyawirawaithaka4993]

Thank you!

[@wingeddragonra3953]

Professor, you don't autoclave the TSA agar?

[@shahriarhabib1859]

Thank you sir.

[@dimaal8477]

Thank you.

[@user-cx2qz3dp9x]

Does one virus infects only one host-cell? Or can multiple viruses attack the same cell? Can this interfere with the calculation of PFU/ml?

[@artidamsri6582]

Thank you so much

[@athiraaravind3557]

Very informative.

[@TheProductiveGeneralist]

it's cool to put a face on the main voice on TWIV :) cool vids

[@renatabudaszewski2565]

And why is it usually used a 6 well plate? Specially if you dilute to -8.

[@kingarthur326]

Didn't realize Robin Williams was a virology professor

[@cactikaty]

Thank you

[@muhsinedham9931]

thank you

[@dwayneharris4787]

Virologists or student virologist please my question. Is the 'virus sample', isolated, purified, visualised, and its morphology and genetic sequence described BEFORE adding it to a cell culture? If this is not done, the process seems very anti-scientific. I find it very interesting that a virus is never identified directly from a sick person.

[@YoYo-sv3km]

Great :)

[@renatabudaszewski2565]

Why plaque assay and not TCID50?

[@elizabethoforiwakumi3766]

Could i come work for you?

[@captglasspac]

5:40 Clean that water bath!

[@daniaapril6448]

this is great..but i can't du a plaque assay, because a virus i should be working on grows only in a suspension culture :(

[@sawairagul251]

👌👌👌

[@Micro-life]

thnk u sir fo such a clear xplanatn...thnks a lot😊😊😊😊

[@traiandanciu8139]

We need special glove to protect forearm skin

[@jrussell243]

It is a pretty wall

[@TehCycleDiaries]

love the video as always, but seems a bit morbid to have a "favourite" virus... especially one which causes the still causes so much devastation... is like "WWII and my favourite war"... "The third crusade is my favourite"

[@______6879]

But WWII is my favorite war....

[@brysonjones9162]

i like olio virus too!!!1!!1!!1

[@drewetpa]

Ha ha, you said counting the virus titre is easy. In recent podcasts you get all 'grumpy' when people talk in terms of virus titre

[@drewetpa]

@Jones Ailsa Did you mean to post this as a reply to me? Was it a comment on the YT video or intended for someone else.. I guess I should congratulate you, nevertheless, on testing negative for herpes.

[@mothank35]

That water bath was disgusting

[@estherbutcher1126]

Look at you

[@fips001]

so much plastic waste ^^

[@noonesflower]

''If I held up this tube and asked you how many zika viruses were in it?'' ----I would say probably you are holding up a phial of pink koolaid as a prop for the show. Be real.